Alstom SHPM 101 - Gating of Comparator Output; Level Detector

SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Appendix A
Page 49 of 71
Figure 56: Level detector
Figure 55: Gating of comparator output
&
| I Z| >SETTING
180°>arg( )>0°
LEVEL
DETECTOR
V – IZ
COMPARATOR
V
POL
IZ
TRIP
B
A
A
B
V
IN
t2
V
REF
t1
START
NO
YES
NO NO
YES
YES
YES
NO
NO
RESET TIME t1
RESET FLAG
HAS
TIMER t1
FINISHED?
SET FLAG
RESET TIMER t2
START TIMER t2
FLAG RESET
TIMERS RESET
V
REF
NORMAL
OUTPUT LOW
START TIMER t1
IS FLAG SET?
IS
TIMER t1
RESET ?
IS
TIMER t2
RUNNING?
IS
MODULUS OF
INSTANTANEOUS VALUE OF
V
I N
> V
REF
?
INITIAL CONDITIONS
LET V
REF
=V
REF
X 0.9
SET OUTPUT HIGH
SET OUTPUT LOW
RESTORE V
REF